This is the season to be miserable. Every other person seems to be down with something. But what?

Is it "just a cold" or are you suffering from something more serious like the flu, bronchitis, sinusitis or perhaps pneumonia? Or could it be an allergy? Knowing what you have can make a big difference in how you feel, the treatment you require and your chances for relapse and lingering fatigue.

There is an understandable resistance about consulting a doctor for what you think is a cold or other seemingly minor infection, especially if you're still able to muddle through your day. And there is even greater resistance about taking antibiotics, which are widely abused and overused. But sometimes such treatment is necessary, and the sooner it is started, the faster the recovery and the fewer the complications.

The wise reader will save this column, since the information is bound to come in handy, if not for you then for a relative or friend.

One of the best ways to distinguish between a cold and the flu is by how the illness began. If it crept up on you, starting perhaps with a scratchy throat, sniffles or sneezes, and gradually progressed into a runny or stuffy nose, a sore throat and/or cough, in all likelihood you have a cold -- an upper respiratory infection with one of the 200 viral strains known to cause the common cold.

You may feel a little chilled and achy and possibly run a low-grade fever (no more than 100 degrees for adults and 102 for infants and young children), but the aches will not be severe enough to keep you from going about your business, though you might prefer to go to bed.

Most colds resolve without treatment within a week to 10 days. Longer than that, and chances are you've developed a complication, a bacterial infection like sinusitis or bronchitis that warrants medical consultation and, usually, a prescription for antibiotics to shake the symptoms and malaise.

On the other hand, the flu comes on suddenly and leaves you feeling exhausted. Fevers tend to run high -- 102 to 104 -- and you're likely to ache all over, in muscles you didn't even know you had. Add in extreme fatigue and weakness and you may not be able to do anything but lie in bed and sleep. Working or playing with the flu is usually very difficult, even for those of strong will and stamina.

The upper respiratory symptoms that are the hallmark of colds -- runny or stuffy nose and sneezing -- only sometimes occur with influenza. And while the sore throat of a cold usually disappears in a day or two, the sore throat that accompanies the flu usually worsens by the second or third day. Also, with the flu, the lower respiratory tract is commonly attacked by the culprit virus, leaving the bronchial tubes wracked with a hacking cough.

The flu can also hit below the belt, causing vomiting and diarrhea, especially in children and young adults. This never happens with a cold. When flu attacks the digestive tract, it may be impossible for days to keep down anything that is more nourishing than water or tea. (This symptom is not to be confused with what is loosely called "intestinal flu," which is not a form of influenza at all and has none of the achiness and respiratory symptoms.)

The flu is likely to disappear as abruptly as it started, usually within three to seven days, though it often leaves a legacy of fatigue and depression that can last for weeks.

A colleague's problem started with a cold that just didn't quit, leaving her very tired and understandably dispirited for weeks. Her doctor thought she had chronic fatigue syndrome and suggested Prozac to lift her spirits. Finding neither conclusion acceptable, she consulted another doctor who properly diagnosed a sinus infection and prescribed an antibiotic that restored her vitality in two days.

More often than most people realize, colds that linger are no longer colds but have evolved into bacterial infections of the ears, sinuses or bronchial tubes. These infections gain a foothold when the cold symptoms weaken defenses and impair drainage in the respiratory tract.

When a cold lasts for weeks, when the nasal discharge becomes thick and yellow or greenish and a headache or painful pressure develops in the face, cheeks, upper teeth or around the eyes, chances are you've got a sinus infection. Though these infections sometimes resolve with simple home remedies like hot compresses, an antibiotic is often needed. When the infection hits the ear, the intense pain and sense of fullness in the ear is unmistakable; here again, an antibiotic is likely to be prescribed.

A cold and, more commonly, the flu can also develop into bronchitis or even pneumonia. When a deep, tight or productive cough (i.e., one that brings up thick mucus) accompanies or follows a viral infection, think bronchitis. You might try self-treatment with an expectorant and gallons of fluids, but chances are you'll need an antibiotic to wipe out the infection if bacteria are the cause.

Strep throat can be another source of confusion. Like a cold, it often begins with a sore throat and fever, but the throat quickly becomes so sore and swollen that swallowing water can be a problem. Fevers, too, tend to run high. If a throat culture confirms a streptococcal infection, 10 days of antibiotics are needed to eradicate the bacteria and prevent them from infecting the heart valves (rheumatic fever) or kidneys (glomerulonephritis) and causing permanent organ damage.

Don't assume that because it is winter and few pollen-producing plants are in bloom you cannot be suffering from a nasal allergy. Winter has its share of respiratory allergens -- dust mites galore (especially when the heat is on), mold spores (do you burn wood in a fireplace?) and pets (their saliva harbors the allergen) are the leading candidates. Symptoms may be aggravated by scented candles, smoke, even cooking fumes.

Sleep and rest
During the deepest levels of sleep, potent immune enhancing compounds are released and immune functions are greatly increased. The value of sleep and rest during a cold cannot be overemphasized.

Liquids
Liquid consumption offers several benefits. When the mucous membranes lining the respiratory tract get dehydrated, they provide a more hospitable environment for the virus. Consuming plenty of liquids and/or using a vaporizer maintains a moist respiratory tract that repels viral infection. Drinking plenty of liquids will also improve the function of the white blood cells and help circulate antibodies produced in response to infection.

Nutrition
Vitamin C has been shown to shorten the course of the common cold. It has antiviral and antibacterial effects vital to host resistance. Many immunostimulatory effects have been demonstrated, including enhancing white blood cell production and increasing interferon levels, antibody response, secretion of thymic hormones, and increasing the integrity of connective tissue by helping heal damaged mucous membranes.
Zinc is a critical nutrient of immunity involved in many immune mechanisms, including both cell-mediated and antibody-mediated immunity. Like vitamin C it possess direct antiviral activity, including those that cause "the common cold." Zinc lozenges produce a local concentration high enough to inhibit replication of the cold virus.

Botanical medicines
Pharmaceutical antibiotics have no effect on viruses and can weaken the immune system. Many herbs have significant antibiotic action against bacteria and viruses and a far safer. Herbs are much more than "natural" antibiotics. Several herbs have shown remarkable effects in stimulating our own immune mechanisms. There are a number of special chemical factors which enhance the immune system: interferon, interleuken II, complement, etc. These compounds are produced by various white blood cells and are extremely important in activating the them to destroy cancer cells and viruses. Interferon binds to cell surfaces and stimulates the synthesis of proteins that prevent viral infection. Echinacea is remarkable in its ability to stimulate the production and action of a number of chemical mediators of immunity, but especially interferon. Astragalus has also been shown to enhance the synthesis and secretion of interferon. Modern research is upholding what herbal practitioners have known for thousands of years: herbs work with our bodies systems to promote health. The following herbs represent some of the most potent herbal enhancers of the immune system:
Echinacea is a perennial plant native to the midwestern states and was used by native Americans and an antiseptic. Its major component, inulin, is an activator of the alternative complement pathway, responsible for increasing non- specific host defense mechanisms like the neutralization of viruses, destruction of bacteria, and increasing the migration of white blood cells to areas of infection. It has also been shown to increase properdin levels, the body's natural activator of the alternate complement pathway. It also has profound immunostimulatory effects, increasing the production and secretion of interferon. The resultant effect is enhanced T cell reproduction, macrophage phagocytosis (the engulfment and destruction of bacteria or viruses) antibody binding, natural killer-cell activity, and increased levels of circulating neutrophils (white blood cells primarily responsible for defense against bacteria).
Goldenseal is a perennial herb native to eastern North America and was also used by native Americans for infections. It has a high content of biologically active alkaloids which are effective against a wide range of harmful organisms. Like Echinacea, it also has immunostimulatory activity.
Baptista has traditionally been used in the treatment of infectious conditions, particularly of the upper respiratory tract. Its mmunostimulatory activity includes the enhancement of white cell destruction of viruses and bacteria, production and activation of lymph cells, and the production of antibodies. It is appears to have particulary uselfulness for tonsillitis, pharyngitis, and lymphadenitis.
Astragalus has a well respected history of use in Chinese medicine as a valuable tonic for strengthening the body's resistance. It is also valuable in chronic fatigue syndrome. It can enhance the production of interferon, and reduce the incidence and shorten the course of the "common cold."